The present invention generally relates to an apparatus for processing a microelectronic workpiece. More particularly, the present invention is directed to a microelectronic workpiece processing tool having a reactor that includes a paddle assembly, which moves relative to the workpiece for facilitating the processing of a microelectronic workpiece. For purposes of the present application, a microelectronic workpiece is defined to include a substrate upon which microelectronic circuits or components, data storage elements or layers, and/or micro-mechanical elements are formed.
During the processing of a workpiece, the portion of the workpiece to be processed is often exposed to a processing fluid designed to bring about a desired alteration of the surface of the workpiece. In many instances, the alteration of the surface of the workpiece involves a particular chemical reaction that takes place at the surface. As the reaction takes place at the surface, the reactants from the processing fluid are consumed and/or chemical byproducts are released into the fluid. In order to maintain the desired forward reaction at the workpiece surface at optimal levels, it is often necessary to continuously replenish the processing fluid proximate the workpiece surface that is processed.
One known technique for replenishing the processing fluid proximate the workpiece surface includes spinning the workpiece to agitate the processing fluid near the surface of the workpiece. In this way, relatively fresh processing fluid whose chemical concentrations have not yet been significantly affected by the localized reactions taking place at the surface of the workpiece will continuously replace the spent processing fluid.
There are instances, however, in which spinning a workpiece relative to the processing fluid is undesirable. For example, rotation of the workpiece may be undesirable when electroplating certain materials onto a workpiece where the deposited material must be uniformly aligned in a particular magnetically polarized direction. Such processes are used in the formation of certain read/write heads In such processes, an external magnetic field is applied to the processing area, which magnetically aligns the material to be plated prior to the material being deposited. If the workpiece within the magnetic field were to be spun, the orientation of the magnetic field with respect to the workpiece would be continuously changing. A continuously changing orientation of the magnetic field would disrupt the formation of the desired magnetically uniform deposition.
In view of the foregoing, other methods for agitating the processing fluid have been developed for insuring the continuous replenishment of the processing fluid proximate the workpiece surface under process. Namely, a paddle is used that physically moves through the processing fluid relative to and proximate to the workpiece surface to thereby agitate the processing fluid near the surface. Such agitation has the effect of replenishing the processing fluid proximate the workpiece surface.
In addition to agitating the processing fluid, the paddle motion has been separately developed to limit processing to a portion of the area of the workpiece surface that is to be processed. In essence, this provides localized control of the processing of the workpiece, including localized control of the application of processing fluids. To this end, the paddle is directed to move across the workpiece in a predefined manner, selectively applying chemistry and/or processing power at any one time to only a portion of the total area to be processed. Techniques which provide both linear and spiral movement of the paddle relative to the workpiece have been previously developed.
In these instances, concurrent processing of the entire portion of the workpiece to be processed can produce undesirable or incomplete results. In at least one instance a paddle has been used to produce a controlled linear flow of the processing across the area to be processed. The paddle is used to selectively supply processing fluid to only a portion of the surface at any one time. The direction of the processing is similarly controlled. The direction of the processing is controlled in processes where the specific order in which the separate portions of the surface are processed is important.
One example of where the application of processing fluid for processing a workpiece in a controlled fashion has been used is in the electroetching or removal of a material from the surface of the workpiece. In such instances, the material being removed provides the conductive path for supplying a necessary portion of the processing power. As a result, the removal of material must be performed in a generally controlled manner, since global removal of the entire conductive surface of the workpiece to be processed would result in the etching away of portions of the conductive layer located proximate to the source of processing power prior to those areas located remote from the processing power source. This would result in electrical isolation of such remote areas from the processing power prior to the completion of the electroetch in those areas. By selectively applying the etching process and beginning with the areas furthest from the processing power source, the likelihood of electrically isolating a region prior to completing the electroetching in that region is reduced.
In addition to supplying processing fluid to the surface of the workpiece, previous paddles have been similarly equipped with a conductive surface coupled to a power source. Accordingly, processing power can be supplied to the paddle for the purpose of acting as an electrode in an electrochemical process.
However, in known systems, the processing fluid supplied by the paddle has been allowed to run off of the workpiece and the paddle into the processing chamber. Effectively the processing fluid associated with the electroetch process is then unavoidably present throughout the processing chamber. The presence of processing fluid throughout the processing chamber may preclude the use of the same processing chamber for use in a subsequent processing step, especially where a different processing fluid is used. The processing fluid present from the preceding step may provide a source of chemical contamination or may result in the mixing of chemicals, which may produce undesirable results. Accordingly, under these circumstances, it may be very difficult to use the same processing chamber for other processing steps. As such, further processing reactors must be incorporated into the processing tool in order to execute the further processing steps. This results in an increased cost for the tool as well as an increase in the required tool footprint.
In view of the cross-contamination issues noted above, the development of paddles for providing localized processing of the surface of the workpiece has proceeded independent of the development of paddles for agitating a processing fluid proximate to the workpiece. The risk of cross contamination of the chemistries between each of the steps renders the co-development of these differing approaches counter-intuitive. As a result, the use of a paddle assembly within a given processing chamber has been effectively limited to a single processing step or purpose. The present inventors, however, have ignored such conventional wisdom and have developed a reactor for processing a microelectronic workpiece that employs a multi-purpose paddle assembly design that effectively reduces and/or eliminates many of the cross-contamination issues. In addition to the unique paddle assembly design, the reactor further incorporates unique features that enable it to be used to affect multiple processes at a single processing station. Still further, novel microelectronic workpiece processes and processing sequences naturally evolve from the unique reactor and/or paddle assembly design.